In a typical wireless communication network, wireless devices, also known as wireless communication devices, Mobile Stations (MS), stations (STA) and/or user equipments (UE), communicate via a Radio Access Network (RAN) with one or more core networks (CN). The RAN covers a geographical area which is divided into service areas or cell areas, which may also be referred to as a beam or a beam group, with each service area or cell area being served by a radio network node such as a radio access node e.g., a Radio Base Station (RBS), which sometimes may be referred to as e.g., BTS (Base Transceiver Station), evolved Node B (“eNB”), “eNodeB”, “NodeB”, or “B node”, depending on the technology and terminology used. A service area or cell area is a geographical area where radio coverage is provided by the radio network node. The radio network node communicates over an air interface operating on radio frequencies with the wireless device within range of the radio network node.
The base stations may be of different classes such as e.g. Wide Area Base Stations, Medium Range Base Stations, Local Area Base Stations and Home Base Stations, based on transmission power and thereby also cell size. A cell is the geographical area where radio coverage is provided by the base station at a base station site. One base station, situated on the base station site, may serve one or several cells. Further, each base station may support one or several communication technologies. The base stations communicate over the air interface operating on radio frequencies with the terminals within range of the base stations. In the context of this disclosure, the expression Downlink (DL) is used for the transmission path from the base station to the wireless device. The expression Uplink (UL) is used for the transmission path in the opposite direction i.e. from the wireless device to the base station.
A Universal Mobile Telecommunications System (UMTS) is a third generation (3G) telecommunication network, which evolved from the second generation (2G) Global System for Mobile telephony (GSM). The UMTS terrestrial radio access network (UTRAN) is essentially a RAN using wideband code division multiple access (WCDMA) and/or High Speed Packet Access (HSPA) for user equipments. In a forum known as the Third Generation Partnership Project (3GPP), telecommunications suppliers propose and agree upon standards for third generation networks, and investigate enhanced data rate and radio capacity. In some RANs, e.g. as in UMTS, several radio network nodes may be connected, e.g., by landlines or microwave, to a controller node, such as a radio network controller (RNC) or a base station controller (BSC), which supervises and coordinates various activities of the plural radio network nodes connected thereto. This type of connection is sometimes referred to as a backhaul connection. The RNCs and BSCs are typically connected to one or more core networks.
Positioning
At RAN#72, a Work item on “Positioning Enhancements for GERAN” was approved, see RP-161260, “New Work Item on Positioning Enhancements for GERAN”, source Ericsson LM, Orange, MediaTek Inc., Sierra Wireless, Nokia, wherein one candidate method for realizing improved accuracy when determining the position of a mobile station (MS) is Timing Advance (TA) multilateration, see also RP-161034, “Positioning Enhancements for GERAN—introducing TA trilateration”, source Ericsson LM. RAN#72. TA multilateration may be understood as relying on establishing the MS position based on TA values in multiple cells.
At RAN1#86, a proposal based on a similar approach was made also to support positioning of Narrow Band-Internet of Things (NB-IoT) mobiles.
TA may be understood as a measure of the propagation delay between a BTS and the MS. Since the speed by which radio waves travel is known, the distance between the BTS and the MS may be derived. Further, if the TA applicable to a MS is measured within multiple BTSs, and the positions of these BTSs are known, the position of the MS may be derived using the measured TA values. Measurement of TA may require that the MS synchronizes to each neighbor BTS and transmits a signal time-aligned with the estimated timing of the downlink channel received from each BTS. The BTS may measure the time difference between its own time reference for the downlink channel, and the timing of the received signal, transmitted by the MS. This time difference may be understood to be equal to two times the propagation delay between the BTS and the MS. That is, one propagation delay of the synchronization signal from the BTS sent on the downlink channel to the MS, plus one equal propagation delay of the signal transmitted by the MS back to the BTS.
Once the set of TA values are established by the set of one or more BTS used during a given positioning procedure, the position of the device may be derived through a so called Multilateration, or Multilateration procedure, whereby the position of the device may be determined by the intersection of a set of hyperbolic curves associated with each BTS, see FIG. 1. FIG. 1 illustrates a Multilateration procedure involving three base stations, each associated with three TA values, TA1, TA2, and TA3, for a wireless device, located in the center of the image, in the intersection of the indicated set of hyperbolic curves.
The calculation of the position of the device may be typically carried out by the serving positioning node, e.g., a Serving Mobile Location Center (SMLC), which implies that all of the derived timing advance and associated BTS position information may need to be sent to the positioning node that initiated the positioning procedure, that is, the serving positioning node. In some cases, a BTS used during a given positioning procedure may be associated with a non-serving positioning node, in which case the derived timing advance and associated BTS position information available to that BTS may need to be relayed to the serving positioning node.
For the purpose of simplifying the provided herein the following terms may be used according to the descriptions that follow: foreign BTS, local BTS, serving BTS, serving SMLC node, serving Base Station Subsystem (BSS), and non-serving BSS.
A foreign BTS may be understood as a BTS associated with a BSS that uses a positioning node that is different from the positioning node used by the BSS that manages the cell serving the MS when the positioning procedure is initiated. In this case, the derived timing advance information and identity of the corresponding cell is relayed to the serving positioning node using the core network, that is, in this case the BSS has no context for the MS. A context may be understood as information provided to a BSS by the positioning node prior to the positioning node initiating a positioning procedure for a given MS, wherein the BSS manages the cell in which the MS is currently located and wherein the positioning node requests the BSS to begin the positioning procedure for the MS subsequent to providing the BSS with the information used for context establishment. This context information may consist of the logical connection established between the serving BSS and the positioning node established as a result of the serving BSS sending a BSSMAP-LE Perform Location Request message, e.g., as defined in 3GPP TS 49.031 v13.0.0, to the positioning node and/or as a result of the serving BSS sending a BSSMAP-LE Assistance Information Request message, e.g., as defined in 3GPP TS 49.031 v13.0.0, to the positioning node after the logical connection has been established.
A local BTS may be understood as a BTS associated with a different BSS, but still a BSS that uses the same positioning node as the BSS that manages the cell serving the MS when the positioning procedure is initiated. In this case, the derived timing advance information and identity of the corresponding cell is relayed to the serving positioning node using the core network, that is, in this case the BSS has no context for the MS.
A serving BTS may be understood as a BTS associated with a BSS that manages the cell serving the MS when the positioning procedure is initiated. In this case, the derived timing advance information and identity of the corresponding cell is sent directly to the serving positioning node, i.e., in this case the BSS has a context for the MS.
A Serving SMLC node may be understood as the SMLC node that commands a MS to perform the Multilateration procedure, that is, it may send a Radio Resource Location services Protocol (RRLP) Multilateration Request to the MS.
A Serving BSS may be understood as the BSS associated with the serving BTS, that is, the BSS that has context information for the Temporary Logical Link Identity (TLLI) corresponding to a MS, for which the Multilateration procedure has been triggered.
A Non-serving BSS may be understood as a BSS associated with a Foreign BTS, that is, a BSS that does not have context information for the TLLI corresponding to a MS for which the Multilateration procedure has been triggered.
Internet of Things (IoT)
The Internet of Things (IoT) may be understood as an internetworking of communication devices, e.g., physical devices, vehicles, which may also referred to as “connected devices” and “smart devices”, buildings and other items—embedded with electronics, software, sensors, actuators, and network connectivity that may enable these objects to collect and exchange data. The IoT may allow objects to be sensed and/or controlled remotely across an existing network infrastructure.
“Things,” in the IoT sense, may refer to a wide variety of devices such as heart monitoring implants, biochip transponders on farm animals, electric clams in coastal waters, automobiles with built-in sensors, DNA analysis devices for environmental/food/pathogen monitoring, or field operation devices that may assist firefighters in search and rescue operations, home automation devices such as the control and automation of lighting, heating, e.g. a “smart” thermostat, ventilation, air conditioning, and appliances such as washer, dryers, ovens, refrigerators or freezers that may use Wi-Fi for remote monitoring. These devices may collect data with the help of various existing technologies and then autonomously flow the data between other devices.
It is expected that in a near future, the population of Cellular IoT devices will be very large. Various predictions exist, among which one assumes that there will be >60000 devices per square kilometer, and another assumes that there will be 1000000 devices per square kilometer. A large fraction of these devices are expected to be stationary, e.g., gas and electricity meters, vending machines, etc.
Extended Coverage (EC)-GSM-IoT and NB-IoT are two standards for supporting Cellular IoT devices that have been specified by 3GPP TSG 3rd Generation Partnership Project (3GPP) Radio Access Network (GERAN) and TSG RAN.
Machine Type Communication (MTC) has in recent years, especially in the context of the Internet of Things (IoT), shown to be a growing market segment for cellular technologies. An MTC device may be a communication device, typically a wireless communication device or simply wireless device, that is a self and/or automatically controlled unattended machine and that is typically not associated with an active human user in order to generate data traffic. An MTC device may be typically more simple, and typically associated with a more specific application or purpose, than, and in contrast to, a conventional mobile phone or smart phone. MTC involves communication in a wireless communication network to and/or from MTC devices, which communication typically may be of quite different nature and with other requirements than communication associated with e.g. conventional mobile phones and smart phones. In the context of and growth of the IoT it is evidently so that MTC traffic will be increasing and thus needs to be increasingly supported in wireless communication systems.
A general problem related to (re)using existing technologies and systems is that the requirements for the new type of devices are typically different than conventional requirements, e.g. regarding the type and amount of traffic, performance etc. Existing systems have not been developed with these new requirements in mind. Also, traffic generated by new type of devices will typically be taking place in addition to conventional traffic already supported by an existing system, which existing traffic may typically need to continue to be supported by and in the system, preferably without any substantial disturbance and/or deterioration of already supported services and performance.
Any need of modifications of existing systems and technology may need to be considered with the objective of being cost efficient, such as enabled by low complexity modifications, and preferably allowing legacy devices, i.e. devices already being employed, to continue to be used and co-exist with the new type of devices in one and the same wireless communication system.
Due to the predicted ubiquity of the cellular IoT devices, some of the current standardization procedures are focused on providing for standards for low cost wireless devices, which may have restrictions in their operation, such as limited battery life.
However, existing methods for positioning a wireless device, that is, for determining the geographical location of a wireless device, may lead to wasted time-frequency resources, suboptimal positioning accuracy, and/or unnecessary energy consumption. Existing methods for positioning a wireless device are therefore particularly suboptimal for wireless devices with limited battery life, such as low cost cellular IoT devices.